This invention relates to a hinge assembly suited to be used for a foldable cellular telephone, and the like, and more particularly to a hinge assembly capable of enlarging the turn biasing force.
In general, a hinge assembly of this type comprises a circular cylindrical hinge main body, a turnable member turnably but non-movably connected to one end portion of the hinge main body, a movable member movably but non-turnably provided on the hinge main body and disposed opposite the turnable member, and bias means for urging this movable member so as to abut with the turnable member. One of the abutment surfaces of the turnable member and the movable member is provided with a closing direction cam face and an opening direction cam face which are disposed away from each other by a predetermined angle in the circumferential direction. The other abutment surface is provided with a first projection which contacts the closing direction cam face in the vicinity of the closed position and a second projection which contacts the opening direction cam face in the vicinity of the open position.
When the hinge assembly thus constructed is to be used in a foldable cellular telephone, one of the hinge main body and the turnable member is non-turnably connected to a transmission section of the cellular telephone and the other is non-turnably connected to a reception section. When the reception section is located in the vicinity of the closed position, the biasing force of the bias means is converted into a turn biasing force in the closing direction by both the closing direction cam face and first projection. By this turn biasing force, the reception section is turn biased toward the closed position side and held in the closed position where the reception section is in collision with the transmission section. On the other hand, when the reception section is located in the vicinity of the open position, the biasing force of the bias means is converted into a turn biasing force in the opening direction by both the opening direction cam face and second projection. By this turn biasing force, the reception section is held in the open position (see Japanese Patent Application Laid-Open No. H07-11831 and Japanese Patent Application Laid-Open No. H10-65778).
When the hinge assembly is to be attached to the cellular telephone, it is the normal practice that one each of the hinge assemblies is attached to one and the other end portions of the transmission section and the reception section in a direction of the rotation axis. And the reception section is turned with respective to the transmission section through the two hinge assemblies. However, it is inevitable for such two hinge assemblies to have manufacturing errors and attaching errors. Due to those errors, the turnable members of the two hinge assemblies are often slightly displaced in phase. When such displacement in phase should occur, the timing for those two hinge assemblies to start turning of the reception section in the closing or opening direction would be slid, even if one of the hinge assemblies should turn bias the reception section with a turn biasing force of a designed value, the other hinge assembly would turn bias the reception section only with a smaller force than the designed value. As a consequence, the turn biasing force for turning the reception section becomes insufficient in some instances.
Moreover, there would be some cases where the hinge assembly can be attached to only one end side and only a bearing can be attached to the other end side. In those cases, since the reception section is turn biased only by one hinge assembly, the turn biasing force applicable to the receptions section becomes more insufficient.
An object of the present invention is to provide a hinge assembly in which only one hinge assembly, when used in a cellular telephone, for example, can turn the reception section sufficiently. In order to achieve this object, the present invention provides a hinge assembly comprising a hinge main body, a turnable member turnably disposed at one end side of the hinge main body, a movable member disposed at one end portion of the hinge main body such that the turnable member is movable in a direction of a rotation axis of the turnable member but non-turnable and arranged opposite that end face of the turnable member which is oriented towards the other end side of the hinge main body, and bias means for urging the movable member so as to abut with the turnable member, one of abutment surfaces of the turnable member and the movable member being provided with a projection and the other abutment surface being provided with a cam face for converting a biasing force of the bias means into a turn biasing force for turning the turnable member in one direction by abutment of the cam face with the projection when the turnable member is turned into a predetermined position, characterized in that the hinge assembly further comprises a second turnable member turnably disposed at the other end side of the hinge main body with an axis thereof aligned with the turnable member and non-turnably connected to the turnable member, and a second movable member disposed at the other end portion of the hinge main body such that the second movable member is movable in a direction of a rotation axis of the second turnable member but non-turnable and urged by the bias means so as to abut with that end face of the second turnable member which is oriented towards one end side of the hinge main body, one of abutment surfaces of the second turnable member and the second movable member being provided with a second projection and the other abutment surface being provided with a second cam face for converting a biasing force of the bias means into a turn biasing force which acts in the same direction as the turn biasing force converted by the cam face when the turnable member is turned into the predetermined position.
It is preferred that the turnable member and the second turnable member are non-turnably and non-movably disposed at opposite end portions of a connection shaft which is turnably pierced through the hinge main body. It is more preferred that one of the turnable member and the second turnable member is integrally formed on the connection shaft.
Preferably, a fitting recess for allowing the projection to be detachably fitted therein in accordance with relative turning motion of the turnable member and the movable member is formed in that abutment surface of the abutment surfaces of the turnable member and the movable member on which the cam face is formed, and a second fitting recess for allowing the second projection to be detachably fitted therein in accordance with relative turning motion of the second turnable member and the second movable member is formed in that abutment surface of the abutment surfaces of the second turnable member and the second movable member on which the cam face is formed. It is also preferable that a plurality of the fitting recesses are formed, the fitting recesses are arranged on a circumference about the axis of the turnable member in such a manner as to be away from one another, a plurality of the second fitting recesses are formed, the second fitting recesses are arranged on a circumference about the axis of the second turnable member in such a manner as to be away from one another.
It is also accepted that the fitting recesses and the second fitting recesses are arranged in such a manner as to have mutually different phases in the circumferential directions of the turnable member and the second turnable member, so that the fitting recesses and the second fitting recesses are alternately located in the circumferential directions, or that the fitting recesses and the second fitting recesses are arranged in such a manner as to have a mutually same phase in the circumferential directions of the turnable member and the second turnable member.